[FIXED] Python async function loop + return argument

Issue

I'm trying to create a small script in Python to get Telegram notification and then take action based on message.

I'm struggling to create a loop that listen Telegram and return parsed text I need.

import re
import asyncio
from telethon import TelegramClient, events


def extract_trigger(new_message):
    return re.findall(r'\$(.+?)\b', new_message)

#@client.on(events.NewMessage(chats=user_input_channel))
async def new_message_listener(event):
    #Get Message Text
    new_message = event
    print(extract_coin(str(new_message)))
    if str(new_message).find(message_filter) != -1 :
        trigger = extract_trigger(str(new_message))
        print('Found! ' + trigger[0])
        await client.disconnect()
        return trigger[0]


async def main():
    coro = await new_message_listener(events.NewMessage(chats=user_input_channel))
    trigger = coro
    print(trigger)


api_id = xxxxxx
api_hash = 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxx'
client = TelegramClient('session_read', api_id, api_hash)
user_input_channel = 'https://t.me/mychan'
message_filter = 'Trigger $'

client.start()

if __name__ ==  '__main__':
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())

I'm quite new with Python and have some difficulties with async function. At this point, the script loop and only print "none" variable in the main function.

If I use this small script I'm able to get the message but it's not "looping" on the listener.

from telethon import TelegramClient, events


api_id = xxxxxxx
api_hash = 'xxxxxxxxxxxxxxxxxxxxxxxxxxxx'
client = TelegramClient('session_read', api_id, api_hash)

user_input_channel = 'https://t.me/mychan'

message_filter = 'Trigger $'

client.start()

@client.on(events.NewMessage(chats=user_input_channel))
async def newMessageListener(event):
    #Get Message Text
    newMessage = event.message.message
    if newMessage.find(message_filter) != -1 :
        print('Found! ' + newMessage)
    else:
        print('Not found!')


with client:
    client.run_until_disconnected()

can someone help me with this ?

Solution

The second snippet is correct, but it insists on running the event loop for you using run_until_disconnected. This is just a convenience API, though, and you can instead run the event loop yourself. Your top-level function can fire up the bot and wait for the event callback to provide it with the information it needs, e.g. using an asyncio.Future:

from telethon import TelegramClient, events

api_id = xxxxxxx
api_hash = 'xxxxxxxxxxxxxxxxxxxxxxxxxxxx'

async def get_msg_async():
    client = TelegramClient('session_read', api_id, api_hash)
    user_input_channel = 'https://t.me/mychan'
    message_filter = 'Trigger $'

    found = asyncio.get_event_loop().create_future()

    @client.on(events.NewMessage(chats=user_input_channel))
    async def newMessageListener(event):
        newMessage = event.message.message
        if newMessage.find(message_filter) != -1 :
            print('Found! ' + newMessage)
            found.set_result(newMessage)
        else:
            print('Not found!')

    # start the client
    await client.start()
    # allow the client to run in the background and wait for
    # newMessageListener to provide the message
    return await found

def get_msg():
    return asyncio.run(get_msg_async())

# now in your sync code you should be able to use:
msg = get_msg()

Answered By - user4815162342